#define _CRT_SECURE_NO_WARNINGS  1


class Solution
{
public:
    int lengthOfLongestSubstring(string s)
    {
        int hash[128] = { 0 };
        int left = 0;
        int right = 0;
        int ret = 0;

        while (right < s.size())
        {
            hash[s[right]]++;
            while (hash[s[right]] > 1)
                hash[s[left++]]--;
            ret = max(ret, right - left + 1);

            right++;
        }
        return ret;
    }
};